1. Technical Field
The present invention relates to a tightening operation analysis apparatus, a tightening operation analysis system, a tightening operation analysis program, a tightening operation analysis method, and a tightening tool.
2. Related Art
A torque wrench has been known as a tightening tool to control a tightening torque. The torque wrench is configured to notify a worker that a tightening torque generated by tightening a tightened member such as a bolt and a nut at a tightening point reaches a torque value previously set for the tightening tool (hereinafter “preset torque value”).
In the case of a mechanical torque wrench, when the tightening torque reaches a preset torque value, which is applied by the worker who is holding a casing as a main body of the torque wrench to tighten the tightened member, the casing is turned around a head pin pivotally supporting a head and the casing in a first direction which is the same as the tightening direction to tighten the tightened member. In this case, the head contacts a portion such as the casing and therefore produces a clicking noise and a vibration which can be perceived by the worker. By this means, the worker knows that the tightening torque reaches the preset torque value. After that, when the worker stops applying the force to the torque wrench, the casing turns in a second direction opposite to the first direction (tightening direction), and returns to the initial position. Some mechanical torque wrenches may change the preset torque value by rotating a dial rotating member to adjust the compressive force of a spring.
Here, in order to detect a turning motion of the casing with respect to the head of the mechanical torque wrench, a technologies for detecting a turning motion of the head has been disclosed, for example, in Japanese Patent Application Laid-Open Nos. 2007-283455, 2008-307670 and 2014-037041. JP2007-283455 discloses a technology as a method including: detecting sound generated by the torque bar to output an electric signal corresponding to the sound; analyzing the electric signal and analyzing the presence/absence of sound of the specific pattern to determine whether or not one thread fastening is completed; and integrating the number of threads completing fastening every time fastening of one thread is determined to be completed and outputting the integrated value. JP2008-307670 discloses a technology including use of a hall element to detect an actuation of a toggle mechanism and determine that tightening operation is completed. JP2014-037041 discloses a technology including measuring the rotation angle of an angle wrench in a tightening operation after the torque-detecting mechanism has detected that the specified torque has been reached, on the basis of the angular velocity of the angle wrench around the axis of the object being tightened.
However, with the technologies disclosed in the above-described patent literatures, it is not possible to analyze the load condition of the tightened member, although the mechanical torque wrench can measure the number of tightened members and the rotation angle of the tool during the tightening operation. To be more specific, with the technologies disclosed in the above-described patent literatures, it is not possible to analyze whether the tightening torque has an excessive torque value which exceeds the preset torque value, that is, so called “overtorque.”